This invention relates to the measurement of total iron binding capacity in serum.
Iron is carried in the blood plasma by a specific carrier protein called transferrin. This is a protein of molecular weight 76,000-80,000, which has two sites each capable of binding one iron atom. The total amount of transferrin present determines the total iron binding capacity (T.I.B.C.) of the serum.
The estimation of the T.I.B.C. is an important clinical procedure, with an established role in the diagnosis of such conditions as iron deficiency anaemia and haemochromatosis, and in the monitoring of therapeutic procedures. In iron deficiency states, T.I.B.C. is elevated: in iron overload conditions T.I.B.C. is depressed.
Techniques which are currently used for determination of T.I.B.C. rely on the saturation of transferrin and removal of excess iron from the serum with an adsorbent such as magnesium carbonate (Ramsay, W. N. M.: Clin. Chim. Acta 2 221 (1957)) or an ion exchange resin (Peters, T., Giovanello T. J., Apt, L. and Ross, J. R.; J. Lab. Clin. Med. 48 274 (1956)). Other methods employ direct measurement of the excess iron after saturation, and calculation of unsaturated iron-binding capacity (Williams, H. L., and Conrad, M. E.; J. Lab. Clin. Med. 67 171 (1966); O'Malley, J. A., Hassan, A., Shiley, J., and Traynor, H.; Clin. Chemistry 16 92 (1970)). The most commonly used magnesium carbonate method is subject to error owing to the inclusion of non-transferrin bound iron in the supernatant solution (Ramsay, W. N. M.; J. Clin. Pathol. 26 691 (1973)).
An improved method using an alumina column, which was faster and simpler than the magnesium carbonate method while offering improved accuracy, was previously disclosed by the present inventor (Clin. Chemistry 26 156 (1980)).